Hydrogenation of chlorovinylboranes



Dec. 28, 1965 F. CLARK ETAL HYDROGENATION OF CHLOROVINYLBORANES 2 Sheets-Sheet 1 Filed Jan. 28, 1959 FlG.l

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Benjamin ECIurk John F. Haller INVENTOR.

QM WM 2445 ATTORNEYS Dec. 28, 1965 B. F. CLARK ETAL 3,226,432

HYDROGENATION 0F GHLOROVINYLBORANES Filed Jan. 28, 1959 2 Sheets$heet 2 F IG .3

l-lsl Benjamin F.Clark John F.Haller INVENTORS ATTORNEYS United States Patent C) 3,226,432 HYPROGENATION F CHLOROVINYLBORANES Ben amin F. Clark, Hamden, and John F. Haller, Mount Carmel, Conn, assignors to (Him Mathieson Chemical Corporation, a corporation of Virginia Filed Jan. 28, 1959, Ser. No. 789,742 6 Claims. (Cl. 260-543) This application is a continuation-in-part of our copending application Serial No. 716,510, filed February 20, 1958, now abandoned.

This invention relates to a method for the preparation of alkylboranes from chlorovinylboranes of the class (CICH CH),,(R) BCl where R is an alkyl radical containing from 1 to carbon atoms, a is an integer from 1 to 3, b is an integer from 0 to 2, and where the sum of a plus b is not more than 3.

By the process of this invention, the alkylboranes are prepared by hydrogenatin-g chlorovinylboranes of the above class with molecular hydrogen in the presence of a palladium catalyst.

Suitable chlorovinylboranes inclue dichloro (Z-chlorovinyl)borane, (ClCH=CH)BCl prepared, for example, according to the method described in Gipstein et al. application Serial No. 716,512, filed February 20, 1958 now abandoned; chlorobis-(Z-chlorovinyl)borane (ClCH=CH) BCl prepared, for example, according to the method described in Clark et al. application Serial No. 716,511, filed February 20, 1958, now Patent No. 2,919,291; tris(2- chlorovinyl)borane, (CICH=CH) B, prepared, for example, according to the method described in Clark et al. application Serial No. 716,513, filed February 20, 1958, now Patent No. 2,918,498; chloro(2-chlorovinyl)methylborane ClCH=CH) (CH )BCl chloro 2-chlorovinyl) ethylborane (ClCH CH) (C 11 BCl chloro 2-chlorovinyl) n-propylb orane (ClCH=CH) (C3Hq)BC1 ch1oro(2-chlorovinyl) n-butylborane (ClCH CI-I) (C 11 BCl chloro 2-chlorovinyl) narnylborane (CICH -CH) (C 11 BCl all prepared according to the method described in the application of Perry R. Kippur, Serial No. 789,741, filed of even date, now Patent No. 3,045,044.

The (2-chlorovinyl)ethylalkylboranes corresponding to the chloro(2-chlorovinyl)monoalkylboranes described above can be prepared, for example, by hydrogenating the chloro(2-ehlorovinyl)monoalkylboranes according to the method described in the instant application and reacting the resulting chloroethylmonoalkylborane with tris (2-chlorovinyl)bora11e and separating the desired (2- chlorovinyl)ethylalkylborane from the reaction mixture by fractional distillation. The (2-chlorovinyl)dialkylboranes such as (2-chlorovinyl)di-n-propylborane (ClCH CH) (C H B (2-chlorovinyl) di-n-butylborane (CICH CH) (C H B, and (2-chlorovinyl)di-n-amylborane (ClCH CH) (C H B can be prepared, for example, by reacting the corresponding chlorodialkylborane (which can be prepared by the method described by Booth and Kraus in I. Am. Chem. Soc, vol. 74, at pages 1415-1417, 1952) with tris (2-chlorovinyl)borane and separating the desired (2- chlorovinyl)dialkylborane from the reaction mixture by fractional distillation.

The reaction which takes place when the present process is carried out can be represented by the following equation:

Palladium where a and b have the same meaning as related above.

During the hydrogenation process the temperature of the catalyst bed is maintained at about 20 to :160" C. and preferably within the range of from 40 to C. Also, the hydrogenation is canried out at atmospheric or a moderate pressure preferably in the range from about 0 p.s.i.g. to 50 p.s.i.g. The palladium catalyst employed can be supported on the conventional supports such as carbon, silica, silicon carbide, or asbestos. The molar ratio of the reactants entering the reactor can also be varied widely from about 2 to 20 moles of hydrogen per mole of borane charged.

The products of this invention are valuable chemical intermediates. For example, dichloroethylborane can be utilized to prepare diborane as described in the application of Clark, Serial No. 723,608, filed March 24, 1958, now abandoned. The trialkylboranes can be utilized to prepare diborane as described in the application of Klein et al., Serial No. 614,768, filed October 8, 1956, now Patent No. 2,946,664.

The following examples illustrate but do not limit this invention:

EXAMPLE I The apparatus used in this experiment is shown in FIGURE lot the accompanying drawings. It consisted of glass reactor 1, twelve inches long with an inside diameter of one inch. The reactor 1 was provided with a ten inch jacketed section 2, with inlet 3 and outlet 4, for heating or cooling as required. A sintered glass disc 5 was fixed in reactor 1 and supported the catalyst. Connected to the top of reactor 1 was reactor inlet line 6 into which nitrogen could be introduced by line 7. Line 8 connected with line 6, led to vent line 9 through mercury bubble-01f 10. Hydrogen, introduced through line 11 and rotameter 12, entered reactor 1 through line 13 and line 6. Liquid feed from container 14, introduced through line 15 containing pump 16, entered reactor 1 through line 6. Connected to the lower end of reactor 1 by means of line 17 was product receiving flask 18. Also connected to line 17 by means of line 19 was cold finger type condenser 20 with vent 21. A Dry Ice-acetone mixture at 78 C. was placed in space 22. A weighed quantity of liquid dichloro (2-chlor0vinyl)borane was charged to the 200 ml. glass container 14 in a dry box. To the sintered glass disc 5 in reactor 1 there was added 1 g. of palladium black. The entire system was then assembled as shown in FIG- URE 1. Activation of the palladium catalyst was accomplished by passing hydrogen through the catalyst bed while the reactor jacket temperature was maintained at 100 C. by a water-steam mixture flowing through jacketed section 2 until there was no further formation of water due to the reduction of palladium oxide. The catalyst bed was then heated externally to a temperature of C. by steam flowing through jacketed section 2 and the flow of both reactants, hydrogen and borane, was started. Hydrogen, at the rate of 300 cc. per minute at S.T.P., was metered through rotameter 12 and introduced into the reactor inlet line 6. Dichloro (2-chlorovinyl)borane from container 14 was pumped to reactor inlet line 6 at the rate of 0.376 g. of borane per minute and the two reactants passed downwardly through the catalyst bed. Water was circulated through jacketed section 2 to maintain the reactor temperature at about 140 C. once the exothermic hydrogenation reaction had started. Hydrogenation of the dichloro (2-chlorovinyl) borane began immediately and the product formed was condensed in cold finger type condenser 20 maintained at -78 C. The condensate leaving condenser 20 flowed downwardly into the 200 ml. product receiving flask 18.

Hydrogen chloride formed during the reaction was allowed to escape with the non-condensible gases through the vent line 21. Hydrogen and borane were fed to the reactor for a period of 4.0 hours during this experiment.

At the conclusion of the experiment the liquid borane feed was stopped and the flow of hydrogen was continued until the catalyst was essentially free of borane feed. Next, the hydrogen flow was stopped and the system was flushed with nitrogen. The exit end of the system was then closed and the nitrogen allowed to escape through mercury bubble-off 10 and vent 9. While under a nitrogen atmosphere, the collection flask was removed and conversions and yields were determined by infrared and elemental analysis of the product collected. In this particular experiment, the conversion was 97.5 percent and the yield of dichloroethylborane was 100 percent.

EXAMPLES II THROUGH XII Examples II through XII, utilizing palladium black, palladium on carbon, and palladium on silica, were performed in the same apparatus and in the manner as described in Example I. The pertinent data are set forth in Table 1, following.

The palladium on silica and palladium on carbon catalyst were prepared in the conventional manner by reduction of adsorbed palladium chloride with hydrogen.

EXAMPLE XIII In this example both reactants were fed to the reactor in the vapor phase. The apparatus shown in FIGURE 2 of the drawings was used. In the apparatus of FIGURE 2, the reaction and product collecting and receiving sections were the same as in FIGURE 1 and are numbered accordingly. Connected to the top of reactor 1 was line 23 leading to 200 ml. saturator 24 provided with jacketed section 25 having inlet 26 and outlet 27. Line 23 and the upper portion of saturator 24 were wound with electrical heating tape 28. Saturator 24 was also provided with dip leg 29 and side arm 30. Liquid feed container 31 (200 ml.) was attached to side arm 30. Hydrogen entered the. system through line 32, deoxo unit 33, line 34, drying column 35, line 36, rotameter 37, line 38, three-way stopcock 39, and then either by way of line 40 connected to dip leg 29 or line 41 connected to side arm 30, depending upon the stopcock setting. Nitrogen entered the system through line 42, containing an outlet 43 to a mercury bubble-off and connected to line 34.

The reactor 1 was charged with 6 grams of percent palladium on asbestos and a layer of glass beads was placed on top of the catalyst. The entire system was then assembled and purged with nitrogen, introduced through line 42. Next, the nitrogen flow was stopped and hydrogen introduced through line 32 was passed over the catalyst to activate it by removing as water any oxygen originally present on the catalyst as palladium oxide. During this activation period, reactor jacket 2 was maintained at 100 C. with a water-steam mixture introduced through line 3. Activation was continued until there was no further formation of water due to reduction of the palladium oxide. After the activation had been completed, a weighed quantity of liquid dichloro (2-chlorovinyl) borane was charged to the 200 ml. glass container 31 in a dry box and container 31 was attached to side arm 30 of saturator 24. The three-way stopcock 39 was then adjusted so that hydrogen entering the system entered the saturator through side arm 30. The stopcock on container 31 was then opened and saturator 24 was filled with dichloro (2-chlorovinyl) borane to the desired level. Next, saturator 24 was heated to a temperature of 70 C. by pumping hot water through jacket 25 and saturator outlet line 23 was heated electrically to a skin temperature of 100 C. by means of heating tape 28. When the saturator and saturator outlet line were at the desired temperature and with reactor jacket 2 maintained at 100 C., three-way stopcock 39 was adjusted so that hydrogen entered saturator 24 via dip leg 29 and the gaseous mixture of hydrogen and dichloro (Z-chlorovinyl) borane feed was allowed to pass downwardly over th catalyst bed for a period of 7 hours. I

In this particular experiment, hydrogen entered saturator 24 at the rate of 150 ml./min. at S.T.P. (.0067 mole/min.) and the mole ratio of hydrogen to dichloro (2-chlorovinyl) borane entering the reactor was 10:1.

The hydrogenation reaction started immediately and because the reaction was highly exothermic, the reactor was cooled by water to maintain the temperature at about 100 C. The product, dichloroethylborane, was condensed in cold finger condenser 20 maintained at 78 C. and allowed to run down into collection flask 18. Hydrogen chloride formed during the reaction was not condensed by the condenser and was vented through vent 21.

At the end of the experiment, three-way stopcock 39 was turned to permit hydrogen to enter saturator 24 by means of side arm 30 so that it passed over any liquid in the saturator. This hydrogen purge was continued until no further hydrogen chloride was obtained at the vent. The flow of hydrogen was then stopped and simultaneously nitrogen was allowed to enter the system. Next, the saturator, connecting line 23, and the reactor were allowed to cool to room temperature. Then vent 21 was closed and nitrogen was allowed to escape through the bubble-off. Collection flask 18 was removed under nitrogen pressure and the crude product, which weighed 34.2 grams, was analyzed by elemental and infrared analyses. The conversion was 100 percent and the yield of dichloroethylborane was 97.3 percent.

EXAMPLE XIV This experiment was carried out in the same manner and with the same apparatus described in Example XIII. The experimental details of Example XIV are set forth in Table 2.

EXAMPLE XV In this experiment, a jacketed reactor of one inch inside diameter and fifteen inches in length was utilized. The reactor chamber was loosely packed with the catalyst which was 0.2 percent palladium on 6-mesh charcoal. Liquid chlorobis(2-chlorovinyl)borane was fed from a dropping funnel connected to the top of the reactor tube. An excess of dry hydrogen was fed concurrently downwardly over the catalyst bed, the temperature of which was measured by a thermocouple inserted into the central wall. The reactor outlet was connected to an icecooled receiver and, in addition, exit gases leaving the reactor outlet were passed through a Dry-Ice trap. From the Dry-Ice trap exit gases were sent to a water scrubber to remove hydrogen chloride and finally unreacted hydrogen was vented to the hood after being measured by a wet-test meter. A sampling device was also inserted in the line just before the wettest meter to permit sampling of the off-gas when desired.

In this experiment, 95.9 g. (0.566 mole) of chlorobis(2- chlorovinyl)borane were fed, together with an excess of hydrogen, through the apparatus during a 7.25 hour period. The jacket temperature was maintained at to C. throughout the run.

At the conclusion of the run, the apparatus was thoroughly purged with nitrogen. The contents of the traps were then combined (under nitrogen, since the product is pyrophoric) in a single still pot and distilled (under nitrogen) at atmospheric pressure through an eight-inch Vigreaux column. The crude product, which weighed 54.2 g., on distillation yielded 21.9 g. chlorodiethyl- .borane, representing a 37.2 percent yield and 21.51 g. of dichloroethylborane representing a 34.3 percent yield. The products were identified by infrared and elemental analysis.

EXAMPLE XVI This experiment was carried out in the same manner and in the same apparatus as was used in Example I. The results obtained are shown in Table 3.

EXAMPLES XVI-I AND XVIII In these examples, palladium black was used as a catalyst. A reactor designed specifically for the use of this catalyst was employed. It consisted of a 20 mm. (I.D.) tube, eight inches long, surrounded by a water jacket. A fritted glass disc, sealed into the inner tube at a point just above the lower end of the jacket, served to support the catalyst. A bed, 2-3 mm. thick, of finely ground palladium black was used. Above this was a small, loosely-packed plug of glass wool to distribute the entering liquid and to prevent movement of the catalyst. The location of the catalyst bed in the reactor was designed'to permit quick chilling of the products to reduce, insofar as possible, any side reactions induced by the byproduct hydrogen chloride. Auxiliary equipment and method of operation were the same as described in Example IV.

' Operating data for Examples XVII and XVIII are shown in Table 3.

EXAMPLES XIX THROUGH XXI Table 2 H rate, cc./-rnin. (S.T.P) 200 H rate, moles/min. .0089 5 Mole ratio, H /C H BCl 3/1 Time, hrs. 3 Weight of crude product, g. 60.4 Percent conversion 96.5 Percent yield 99.8 Wt. Of C2H5BCI2 obtained Table 3 Example No- XVI XVII XVIII Expt. N0 4 13 14 (ClCH=CH)2BCl fed;

G 81.6 104.3 99.3 es 0. 482 0. 616 0. 586 12.3 5 5 Catalyst 2% Pd on C Pd black Pd black 85-90 100 80 7 12.25 9.5 46.0 71.0 53.6

4. 32 1.15 1.68 Moles 0. 037 0. 010 0. 014 ClCI-I=OHBC1:

Grams Moles (C1CH=CH)2BC1:

. 28. 69 23. 02 0. 0.786 0. 647 In these three experiments, chloro(2-chlorov1nyl)ethyl- 35 GZHgBCh: 18 78 lg 87 13 9 n in v ri mixed f streams was hydroganated M35531:1:331:11: 6.110 0.119 0.159 in the presence of palladlum black to form chlorodiethyl- (0111 2 0 23 23 27 4 home. The apparatus shown FIGURE 1 was p M00211:3:211:33: 03225 0. 227 0.253 except that the reactor had a diameter of one-half 1nch. g g figg g gg s gg Infxangples XIIX ancli )1Q0(, 0.5 gram of cgtalysfi was ulseg 40 cgigg g f fia 3 2g 31 i an in xamp e XX gram was use e met 0 2 s 2 V 2 Percen I of operation was the same as that described in Example I. .5%}??? meld percent"" 7 3 The experimental details and results obtained in these (CzHs)2BC1/G2H5BC1 1. 33 1.27 2.10 examples are set forth in Table 4.

Table 1 HYDRO GENATION OF DICHLOR0(2 CHLOROVINYL)BORANE Catalyst, Jacket Catalyst Borane Hydrogen, Duration Composition 01 Percent Percent Exam. Catalyst grams temp., C. temp, C. g./min. celmiu. of run, starting material, conv. yield 1 hrs. Wt. percent II Pd black 1 40 130 0.376 300 4.0 94% ClCHCHBCl2 99. 2 90. 8 III 0.2% Pd on 4-6 30 80 0.10 160 6. 0 91% CICHOHB 01 75. 3 87 mesh carbon. IV 0.2% Pd on 4-6 30 80 0.08 160 7. 91% ClCHCHBC1 96. 5 62. 5

mesh carbon. 0.2% Pd on 4-6 30 0. 045 160 7. 2 91% ClCHCHBCl 82. 5

mesh carbon. VI 2% Pd1o1S 660+B0 12. 3 0.54 300 0. 5 89.2% ClCHCHB C12. 93 94 111981 1 2. VII 0.2% Pd on -12 42. 0 100 0. 60 285 0. 5 92.8% CICHCHBCIL 63 100 +16 mesh SiOz. VIII 5.0% Pd on -12 25. 0 100 0. 53 285 2. 25 93% 0101101113 01 74 100 +16 mesh SiOz. IX 2.8% Pd on -28 24 60 60-100 0.73 220 3. 0 51% 0101101113012, 23. 6 100 +35 mesh S102. 45% CQH5B C12.

2.8% Pd on -28 24 70 80-85 0.82 220 3. 0 51% ClCHCHBClg, 76. 3 100 +35 mesh S102. C2HsB C12 XI 2.8% Pd on 28 24 80 80-100 0.76 220 1. 2 51% 0101101113012, 95.6 95.6

+35 mesh S102. 45% CzHsB C12 XII--. 2.8% Pd on 28 24 100 100-110 0.76 220 3. 0 51% ClCHCHB 012, 98. 4 100 +35 mesh 810;. 45% 0 11 1301 Table 4 Example Jacket Catalyst Feed, g./inin. Hydrogen, Duration of Composition oi starting material, Percent Percent tc1np., O. tcmp., C. cc./inin. run, hrs. wt. percent conv. yield XIX 60 140 0. 37 650 0.75 80% (CICHCI DOZHB Cl, 89.7 100 (ClCHCH)zBCl. XX 60 90 0.37 400 1.83 54.9% (ClCHCH)(CzH5)BCl, 85. 5 100 45.1% C2H5BClz. XXI 60 8588 0.356 290 1. 33 32.7% (CICHCH) (C2H5)BCI, 100 100 18.6% ClCHCHB Ch, 43.7% 86. 5 100 EXAMPLES XXII The apparatus consisted of three scrubbing bottles connected in series, each containing about 100 milliliters of Fiesers solution (16 grams sodium hydrosulfite, 13.3 grams sodium hydroxide and 4 grams sodium anthraquinone beta-sulfonate in 100 ml. of water). Nitrogen and hydrogen inlets were provided to the first scrubbing bottle and an outlet from the scrubbing bottle train was connected to the bottom of a drying tower which contained anhydrous calcium sulfate. The top of the drying tower was connected to a gas meter, the outlet of which was attached to the top of the reactor proper.

The reactor 50 shown in FIGURE 3 of the accompanying drawings consisted of a mm. outside diameter glass tube surrounded by water jacket 51 six inches long. A fritted glass disk 52 sealed into the inner tube at a point just above the lower end of the jacket served to support the catalyst. A bad 53 from 2 to 3 cm. in thickness of the individual catalyst was used. Above the catalyst bed was a small loosely packed plug 54 of glass wool which served to distribute the entering liquid and to prevent movement (erosion) of the catalyst.

were introduced into the apparatus. At the conclusion of the reaction period, the equipment was again thoroughly flushed with nitrogen. The contents of the Dry-Ice trap and ice-cooled receiver were combined and distilled through a 12-inch column filled with A5 inch glass helices. The portion boiling up to 100 C. at atmospheric pressure was collected and the products obtained identified by infrared analysis and by boiling point.

Of the original 90.1 grams (0.461 mole) of tris (Z-chlorovinyl) borane fed, 36.45 grams or 38.0 percent were converted to hydrogenated products as follows: ethyl boron dichloride, 0.4 gram (2.3 percent yield); diethyl boron chloride, 7.57 grams (41.8 percent yield); and triethylborane, 7.88 grams (46.4 percent yield).

In this experiment, the reactor was operated under 'a back pressure of 5 inches of Hg.

EXAMPLES XXIII THROUGH XXX A number of additional experiments using palladium black were carried out utilizing the apparatus described in Example XXII. Information concerning these experiments is set forth in Table 5.

Table 5 Example Number XXIII XXIV XXV XXVI XXV II XXVIII XXIX XXX Tris (2-ehlorovinyl) borane fed, gm 77. 3 178. 9 121.7 78.8 90.1 67. 3 78.0 64.8 Catalyst weight, grn 3. 8 3. 8 3. 8 3.8 3. 8 3. 8 3. 8 3. 8 Reaction temperature, C 705:5 90 70 52-54 88-90 88 30 41-56 Hydrogen fed, gm 31. 3 .5 35.0 14.5 16.0 18. 6 14.3 8.0 Reaction pressure, p.s.i.g 0 0 0 2. 5 2. 5 2. 5 2. 5 2. 5 Crude product, gm 42. 9 86.6 91. 4 47. 4 70.0 34. 6 44. 2 45. 7 Dis (2-chlorovinyl) boron chloride, gm 3. 20 24.71 14. 98 9. 16 19. 18 4.20 5. 69 5. 98 Tris (2chlorovinyl)borane, gm 4. 48 8. 90 38. 14 7. 22 22.05 4. 69 4.52 17.63 I'ICl, m 24. 20 63. 30 16. 20 20. 25 12. 18 21. 10 24. 00 16. 06 Dichloroethyl borane, grn 5. 16 13. 40 11. 14 4.006 0.4 3. 26 3. 32 2. 27 Ohlorodiethyl borane, gm. 18. 87 39. 09 11.57 15. 83 7. 57 13.61 23. 73 7. 27 'Iriethyl borane, gm 7. 15 8. 51 2. 16 3. 93 7. 88 5. 57 l. 6. 64

A pressure-equalizing dropping funnel (not shown) was also connected to the top of the reactor from which liquid tris (2-chlorovinyl) borane was introduced into the re- .actor. There was connected to the bottom of the reactor a round-bottom flask as a product receiver (not shown) which was maintained in a Dry-Ice bath and which served to collect the products issuing from the re- :action zone. The product receiver was provided with an outlet line for volatile materials which was connected to a second Dry Ice trap followed by two water scrubbers con- :nected in series for the removal of hydrogen chloride. Volatile materials issuing from the second Water scrubber were passed through a drying tube, through a gas meter, and finally vented to a hood.

In this first example the catalyst chamber was charged with about 3.8 grams of palladium black and the entire apparatus was thoroughly flushed with nitrogen. The catalyst was then activated by heating in a stream of hydrogen for about hour. Following this, the temper-ature of the reactor was adjusted to 5254 C. and the addition of liquid tris (Z-chlorovinyl) borane begun. During a period of 5 /2 hours, 90.1 grams (0.461 mole) .of tr-is (Z-chlorovinyl) borane were fed into the reactor and during this same period, 8.03 gram moles of hydrogen EXAMPLE XXXI In this experiment a 12 inch glass filter tube provided near the bottom with a filter disc of coarse porosity served as the reactor. The filter tube had an internal diameter of approximately 12 mm. To the top of the filter tube there was attached a dropping funnel for the introduction of liquid tris(2-chlorovinyl)borane into the reactor. An inlet at the top of the reactor was also provided for the introduction of hydrogen. The bottom of the reactor was connected in turn to a collection flask, a Dry-Ice condenser, and finally to two series-arranged C. cold traps. Hydrogen entering the system was passed through a unit to convert any oxygen present .in the hydrogen to water, through a drying column containing calcium chloride for removal of water, and then into the reactor.

The catalyst, which was 5 weight percent palladium on asbestos, was placed on the filter disc to a height of three inches in the reactor. The reactor was heated to 98 C. and the system swept out with a stream of hydrogen. Then liquid tris (2-chlorovinyl) borane at the rate of 0.5-1.0 cc./minute and hydrogen at the rate of 500600 cc./minute (S.T.P.) were introduced simultaneously into the reactor and the liquid product formed was collected in the collection flask. The reaction was carried out over a period of 35 minutes and during this time the reactor temperature was 90-94 C.

By gas chromatographic methods it Was shown that the liquid reaction product contained triethyl borane, diethyl boron chloride and monoethyl boron dichloride. The liquid reaction product contained about 40 weight percent triethylborane and about 50 weight percent diethyl boron chloride as determined by infrared analysis.

It is claimed:

1. A method for converting chlorovinyl groups of chlorovinylboranes to alkyl groups which comprises hydrogenating a chlorovinylborane of the class (ClCI'I H) '(R) BC1 where R is an alkyl radical containing from 1 to 5 carbon atoms, a is an integer from 1 to 3, b is an integer from 0 to 2, and the sum of a plus b is not over 3, with molecular hydrogen at a temperature of from 20 to 160 C. and

at a pressure of from 0 p.s.i.g. to p.s.i.g. While the reactants are in contact with a palladium catalyst.

2. The method of claim 1 wherein the chlorovinylborane is dich1oro( 2-chlorovinyl)borane.

3. The method of claim 1 wherein the chlorovinylborane is chlorobis(2-chlorovinyl)borane.

4. The method of claim 1 wherein the chlorovinylborane is chloro(Z-chlorovinyl)ethylborane.

5. The method of claim 1 wherein the chlorov-inylborane is tris(2-chlorovinyl)borane.

6. The method of claim 1 wherein the hydrogenation is carried out at a temperature within the range of 40 C. to C.

No references cited.

LORRAINE A. WEINBERGER, Primary Examiner.

ROGER L. CAMPBELL, LEON D. ROSDOL,

Examiners. 

1. A METHOD FOR CONVERTING CHLOROVINYL GROUPS OF CHLOROVINYLBORANES TO ALKYL GROUPS WHICH COMPRISES HYDROGENATING A CHLOROVINYLBORANE OF THE CLASS 